Re: [PATCH v4 15/39] x86/resctrl: Move monitor exit work to a resctrl exit call

[Reinette Chatre <reinette.chatre@intel.com>]

Hi James,

On 8/2/24 10:28 AM, James Morse wrote:
> rdt_put_mon_l3_config() is called via the architecture's
> resctrl_arch_exit() call, and appears to free the rmid_ptrs[]
> and closid_num_dirty_rmid[] arrays. In reality this code is marked
> __exit, and is removed by the linker as resctrl can't be built
> as a module.
> 
> To separate the filesystem and architecture parts of resctrl,
> this free()ing work needs to be triggered by the filesystem,
> as these structures belong to the filesystem code.
> 
> Rename rdt_put_mon_l3_config() resctrl_mon_resource_exit()
> and call it from resctrl_exit(). The kfree() is currently
> dependent on r->mon_capable.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
> ---
> Changes since v3:
>   * Moved r->mon_capable check under the lock.
>   * Dropped references to resctrl_mon_resource_init() from the commit message.
>   * Fixed more resctrl typos,
> 
> Changes since v2:
>   * Dropped __exit as needed in the next patch.

Is this still relevant? It is unclear to me why __exit is dropped here.

> 
> Change since v1:
>   * [Commit message only] Typo fixes:
>     s/restrl/resctrl/g
>     s/resctl/resctrl/g
> 
>   * [Commit message only] Reword second paragraph to remove reference to
>     the MPAM error interrupt, which provides background rationale for a
>     later patch rather than for this patch, and so it is not really
>     relevant here.
> ---
>   arch/x86/kernel/cpu/resctrl/core.c     |  5 -----
>   arch/x86/kernel/cpu/resctrl/internal.h |  2 +-
>   arch/x86/kernel/cpu/resctrl/monitor.c  | 12 +++++++++---
>   arch/x86/kernel/cpu/resctrl/rdtgroup.c |  2 ++
>   4 files changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index 4a0dbdc2da4d..9d4d64b4e357 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -1101,14 +1101,9 @@ late_initcall(resctrl_arch_late_init);
>   
>   static void __exit resctrl_arch_exit(void)
>   {
> -	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> -
>   	cpuhp_remove_state(rdt_online);
>   
>   	resctrl_exit();
> -
> -	if (r->mon_capable)
> -		rdt_put_mon_l3_config();
>   }
>   
>   __exitcall(resctrl_arch_exit);
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index d355aa676158..3fdeca6e3d21 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -579,7 +579,7 @@ void closid_free(int closid);
>   int alloc_rmid(u32 closid);
>   void free_rmid(u32 closid, u32 rmid);
>   int rdt_get_mon_l3_config(struct rdt_resource *r);
> -void __exit rdt_put_mon_l3_config(void);
> +void resctrl_mon_resource_exit(void);
>   bool __init rdt_cpu_has(int flag);
>   void mon_event_count(void *info);
>   int rdtgroup_mondata_show(struct seq_file *m, void *arg);
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index 9cdca9d2bbde..afbda09aacf5 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -1044,10 +1044,13 @@ static int dom_data_init(struct rdt_resource *r)
>   	return err;
>   }
>   
> -static void __exit dom_data_exit(void)
> +static void dom_data_exit(struct rdt_resource *r)
>   {
>   	mutex_lock(&rdtgroup_mutex);
>   
> +	if (!r->mon_capable)
> +		goto out_unlock;
> +
>   	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) {
>   		kfree(closid_num_dirty_rmid);
>   		closid_num_dirty_rmid = NULL;
> @@ -1056,6 +1059,7 @@ static void __exit dom_data_exit(void)
>   	kfree(rmid_ptrs);
>   	rmid_ptrs = NULL;
>   
> +out_unlock:
>   	mutex_unlock(&rdtgroup_mutex);
>   }
>   
> @@ -1238,9 +1242,11 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
>   	return 0;
>   }
>   
> -void __exit rdt_put_mon_l3_config(void)
> +void resctrl_mon_resource_exit(void)
>   {
> -	dom_data_exit();
> +	struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);
> +
> +	dom_data_exit(r);
>   }
>   
>   void __init intel_rdt_mbm_apply_quirk(void)
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 1597add37b97..576f6b183980 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -4291,4 +4291,6 @@ void __exit resctrl_exit(void)
>   	debugfs_remove_recursive(debugfs_resctrl);
>   	unregister_filesystem(&rdt_fs_type);
>   	sysfs_remove_mount_point(fs_kobj, "resctrl");
> +
> +	resctrl_mon_resource_exit();
>   }

Reinette